Nanotechnolgy, encompassing imaging, measuring and manipulating matter at scales 100 nanometers and smaller requires precision control of position and of distances between probes, tools, devices and materials at a nano-scale, i.e. nano-positioning. It also requires nanopostioners and other precision mechanical systems designed to move objects over a small range (1-100 micron) with resolution down to a fraction of an atomic diameter (Santosh Devasia et. al (2007), and Alexander H. Slocum (1992)). The objective is to achieve extremely high resolution, accuracy, stability, and reproducibility with a fast response time.
The optimum solution in each application is achieved by judicious mechanical design to package the precision actuators (Neal B Hubbard et. al (2006)) and position sensors (M. Tabib-Azar and A. Garcia-Valenzuela (1995)) for active feedback control of motion. The continuous mechanical structure connecting the material to the probe/tool determining their relative position is only rendered flexible by an actuator allowing change in relative position. Along the mechanical path across the actuator a distance sensor is placed and the information provided by the sensor is fedback to the actuator to control nanomotion, i.e. relative position of the material and the nano tool over time.
In reality the system controls the distance between the end points of the sensor which can be some distance away from the probe and the material we are interested in, leaving centimeters—a short distance, but 107-109 times larger than what we intend to control—of the mechanical path uncontrolled, subject of vibration and thermal expansion. In fact, the practical sizes of the sensors, the complexity of the two or three dimensional arrangement of the actuators and sensors and the required functionalities often require the sensors to be located a “safe distance” from the region of interest, leaving no other options to minimize the effect of the uncontrolled mechanical structure than the often unreliable recourse to special materials and environmental (temperature, pressure, etc.) control of the whole positioning system.